Potentially preventable adverse drug-drug interactions increase morbidity and financial costs to hospitals and third party payers.

This study's purpose is to document the prevalence of potential drug-drug interactions (PDDI) in patients referred to a Physical Medicine and Rehabilitation (PM & R) clinic, to identify risk factors associated with PDDI, and to evaluate physicians'ability to correctly identify these PDDI.

Current medication lists were obtained by questionnaire and confirmed by chart review for 121 consecutive new patients.

The physician-identified PDDI were compared with computer-identified PDDI.